Rattle from Housing Behind Rear View Mirror

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by cooljw, Nov 27, 2020.

  1. cooljw

    cooljw Member

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    Plug-in Advanced
    2016 Prius Four: I have a rattle coming from the black plastic housing that's mounted on the front windshield behind the rear view mirror. Actually I'm quite relieved because for the longest time I thought it was coming from inside the dash, but I digress. Anyone know how to open that thing up? Must be a way to do it at least for removing the rear view mirror from its mount?

    Photo is looking straight up at the thing.

    priusmirror.jpg
     
  2. robsnyder20

    robsnyder20 Active Member

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    Not sure how to remove but I believe they remove that piece when connecting into the comma ai harness, maybe that will give you another avenue of search methods.
     
  3. ihatenoise

    ihatenoise New Member

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    Looks like I'm not alone!!!

    The parts you are looking at are called the "No. 2 forward recognition cover" (the small piece right next to stem to the rearview mirror) and "No. 1 forward recognition cover" (the main body piece)

    Here is a video, not of Prius but you open it the exact same way. Be careful to NOT touch the camera to avoid knocking it out of calibration/ground plane alignment. Maybe you can try put some felt tape around the clips?



    I have the same rattling too. Most of it is due to the replacement windshield that the previously owner put on has mounting points that are slightly different, so the cover just kind of hangs on without being secure. I ended up securing the covers using an intricate matrix of zipties to the windshield mount.

    My current solution is to hot glue the edges to dampen out any high frequency vibrations that occur on the cover when i.e. going over rough roads. It seems to work well so far, but the effectiveness does vary with temperature. I also think I found where the noise is coming from in my case... gonna try to post a photo of that soon.
     
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  4. ihatenoise

    ihatenoise New Member

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    Okay here it is. The red circle is where the rattling comes from sometimes. There's a snap clip around that area so it bumps up against the windshield mount. But now in the winter it's cold and I haven't heard it in a while.

    Noise is caused by vibration (tiny movement). So in a bid to allow the oscillations to decay quickly, I applied some hot glue on the edges of the cover (yellow arrow), and that seems to have worked quite well.

    You can see I also put in some foam double-sided tape at first to try solve the problem. But now I think hot glue works the best, and is easy to remove with a pair of tweezers.

    upload_2021-1-25_0-41-25.png
     
  5. cooljw

    cooljw Member

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    Plug-in Advanced
    Thanks everyone for the suggestions! So far I've been able to avoid having to remove the cover to get rid of the rattle - shifting around the cover has done the trick. I may try hot glue or foam tape next if it comes back.
     
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